Nematoda) from Argentina E

RESEARCH/INVESTIGACIÓN DESCRIPTION OF SOME XIPHINEMA SPECIES POPULATIONS (NEMATODA) FROM ARGENTINA E. J. Chaves1* and E. A. Mondino2 1NEMA-AGRiS, Laboratorio de análisis de nematodos en suelo y plantas, 1900 La Plata, Argentina; 2Laboratório de Biologia do Solo, Depto. de Solos, Universidade Federal Rural do Rio de Janeiro, BR-465, km 7 Seropédica, 23890- 000 RJ-Brasil. *Corresponding author: [email protected] ABSTRACT Chaves, E. J., and E. A. Mondino. 2013. Description of some Xiphinema species populations (nematoda) from Argentina. Nematropica 43:68-77. Observations are reported on the morphology and morphometrics of Argentinian populations of Xiphinema krugi, Xiphinema rivesi, Xiphinema vulgare and Xiphinema surinamense found in cultivated and uncultivated soils from the Buenos Aires, Santa Fe, Tucumán and Misiones Provinces. Key words: Xiphinema, morphology, morphometrics, cultivated. RESUMEN Chaves, E. J. and E. A. Mondino. 2013. Descripción de algunas poblaciones de especies de Xiphinema (nematoda) de Argentina. Nematropica 43:68-77. En el presente trabajo son reportadas observaciones morfométricas y morfológicas de poblaciones Argentinas de Xiphinema krugi, X. rivesi, X. vulgare and X. surinamense encontradas en suelos cultivados y no cultivados de las provincias de Buenos Aires, Santa fe, Tucumán y Misiones. Palabras clave: Xiphinema, morfométricas, morfológicas, cultivado. INTRODUCTION information on the occurrence of Xiphinema species in Argentina is provided in this article. Xiphinema, “the dagger nematode”, is one of the principal genera of plant parasitic nematodes, which MATERIALS AND METHODS is found widely throughout most of the world and is found on all of the continents, except Antarctica. The Soil samples were collected by the first author in economic importance of the genus Xiphinema is related cultivated and uncultivated soils during a survey to the virus vector ability and consequent phytosanitary of plant-parasitic nematodes in several regions of risk of some species, nevertheless, the knowledge on this Argentina between 1978-1980 (Chaves, 1984) and in group of nematodes in Argentina is scarce. Information 1996. Nematodes were extracted with centrifugation- on distribution of these nematodes in Argentina was flotation technique, fixed in hot 4% formaldehyde studied by Luc and Doucet (1990) and Doucet et al. and mounted in pure dehydrated glycerine (de Grisse, (1998), and description of some populations of X. 1969). The specimens were extracted, fixed, measured krugi and X. surinamense from Córdoba and Entre and drawn between 1981-1982 and in 1996. Ríos provinces was provided by Decraemer et al. (1998). The objective of this study was to report our Descriptions observations on the morphology and morphometrics of Argentinian populations of Xiphinema krugi, X. rivesi, Xiphinema krugi Lordello, 1955 X. vulgare and X. surinamense found in cultivated (Table 1-2; Fig. 1, A-H, Fig. 3, B, E); Female (n = 13) and uncultivated soils from the Buenos Aires, Santa Fe, Tucumán and Misiones provinces. Additional Body ventrally arcuate, more or less C-shaped. 68 Description of Xiphinema species from Argentina: Chaves and Mondino 69 Cuticule smooth; internally with transverse striae 0.6 Luc and Hunt (1978) redefinedX. krugi and observed µm. Lateral cord occupying 17% of body width. Lateral a great variation in several biometrical characters. pores usually distinct throughout the body. Dorsal Analysing measurements of the tail and of the anterior and ventral body pores distinct in the anterior body genital branch, they suggested the occurrence of groups region. Head rounded, 6 µm high, 14 µm wide, offset of different geographical origin. Oliveira et al. (2006) by slight constriction. Amphid aperture occupying ½ demonstrated the possibility that X. krugi is a species of head width. Guiding sheath of spear 4-18 µm long, complex comprised of four distinct genotypes and/or its posterior margin 102 µm (94-110) from the anterior cryptic species. Morphometrical data of populations end. Odontophore flanges well developed, 10 µm wide. described here most agrees with PX11 and PX26 Brazil Nerve ring 10-12 µm wide at 209 µm (202-218) from populations (RFLP profile B). the anterior end. Total esophageal length 403 µm (370- 437), the basal bulb of esophagus measuring 94 µm Habitat and localities (85-104) long and 22 µm (20-27) wide. Cardia 10-14 µm long. Hemizonid 6-7 µm wide at 186 µm (173-199) Soil around potato plants in Concepción, Tucumán from the anterior end. Vulva transverse slit, at 736 µm Province; garlic in Médanos and corn in Saladillo, (640-822) from anterior end. Two genital branches, the Buenos Aires Province; strawberry in Coronda, Santa anterior one reduced 92 µm (74-106) long, consisting of Fe Province, collected by E. Chaves 1978-1980. a uterus with distinct large lumen and short pouch-like Eggplant in Helvecia, Santa Fe Province collected by oviduct; between the uterus and oviduct a constriction C. Medera 1979. Table 2 is found formed by a weakly developed sphincter. The posterior genital branch is normally developed 299 µm Xiphinema rivesi Dalmasso, 1969. (202-534) long, consisting of ovary, oviduct, sphincter (Table 3, Fig. 2 A, B, I, Fig. 4); Female (n = 21) and uterus with a wider portion. No spermatozoa, no Z organ. In one female an egg 173 µm long, 43 µm wide Body ventrally arcuate, closed or open C posture, was present near the vagina. Vagina 44-52 % of body tapering toward the extremities. Cuticle smooth, width. Tail conoid with ventral peg of variable length. with 0.6 µm wide transverse striae internally. Lateral Two pairs of caudal pores. Cuticle on tail with minute cord occupying 24-27% of body width. Lateral pores oblique lines. A tail blind terminal canal is present in obscure; dorsal and ventral body pores not seen. Head all specimens. Rectum 37 µm (34-41) long. rounded, almost continuous with the rest of the body, although a slight depression can be noticed. Head 10 Male µm wide. Amphid aperture occupying one half of head Not found. width. Guiding sheat of spear 7.5 µm (6-10) long, posterior margin located at 74 µm (71-79) from anterior Juveniles part of body. Stylet flanges well developed 7 µm (6.5- 8) wide. Nerve ring 8-10 µm wide at 167 µm (153- Resemble females. The elongate tail in the first two 173) from anterior end. Total oesophageal length 338 stages become more conoid and subdigitate in J4 (Fig. µm (314-368); basal bulb 74 µm (70-80) long, 16 µm 1, D-G); Table1 (14-19) wide. Cardia 6-7 µm long. Intestine obscured by lipid granules. Hemizonid 5 µm wide at 141 µm ( Remarks 139-144) from anterior part. Vulva transverse slit, at 985 µm (892-1125) from anterior part. Two genital All the populations of X. krugi here reported are branches, the anterior sligthly shorter or equal to the morphometrically similar to the original description posterior, measuring 157 µm (122-182) and 174 µm (Lordello, 1955) and to the populations described by (145-213), respectively. Uterus small, oviduct simple, Cohn and Sher (1972), Williams and Luc (1977), Luc ovaries reflexed. Sphincter not discernible. Vagina and Hunt (1978), Loof and Sharma (1979), Heyns 23-32% of body width. No Z-organ or spermatozoa. (1977), Ferraz (1980), Ebsary et al. (1984), Oliveira Bacteria present in the ovaries of the all specimens. Tail et al., 2006, and Argentinean populations reported conoid with two pairs of caudal pores. Cuticle on the by Decraemer et al. (1998), and present a tail shape tail with very faint radial striae. An obscure tail blind as shown in figure 1 H. The tail shape of X. krugi canal is present. Prerectum not discernible. Rectum 18 varies from one with a fairly long peg to one without µm (16-20) long. peg (Coomans et al., 2001). The tail is subconoid in original description; regularly ogival with a very Male slight bulge at its extremity to conoid rounded with Not found. distinct ventral peg (Luc and Hunt, 1978); longer with a bluntly knobbed tail terminus and shorter tail with Juveniles rounded terminus in Arkansas and Hawaii populations, Resembles adults in general shape. respectively (Robbins and Ye, 2010). 70 NEMATROPICA Vol. 43, No. 1, 2013 Remarks terminus. Three pairs of caudal pores. Cuticule on the tail with minute oblique lines. Tail blind terminal canal The X. rivesi populations from Argentina show present. Prerectum 502 µm long. Rectum 29 µm long. some differences with respect to the original description (Dalmasso, 1969). In fact, the odontostyle, Male the odontophore and the tail are slightly shorter Not found. and the anterior genital branch is larger than the posterior one in the original description; conversely Juveniles they are similar to the USA populations described Morphologically similar to the adult, except for the by Lamberti and Zacheo (1979) and Wotjowicz et tail length wich is longer in J2 and J3. al. (1982), and the Canada populations described by Ebsary et al., (1984). X. rivesi seems to be the most Remarks widely distributed member of X. americanum group in Argentina, it has a wide host range and is one of Only a female and two juveniles were found. The the five species possessing only three juvenile stages female has similar measurements to both X. vulgare (Robbins et al., 1996). It was synonymized with X. and X. setariae Luc, 1958, but differ however from americanum by Stegarescu (1980), but Wojtowicz et the type of X. vulgare in having shorter odontophore al. (1982) consider X. rivesi as a valid species and add and odontostyle, longer tail length and higher c´ ratio. that the head of X. americanum is slightly offset, its The tail length and c’ value most resemble X. setariae, stylet is shorter and its tail is of a different shape, being but the remaining tail ratios given by Tarjan (1964) more pointed.

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